The most common words in a language are the ones you will meet in almost every conversation, text and video. They are the best investment for a beginner.
In every language a small number of words appears far more often than all the others. Learn the most common few hundred and you can follow the gist of a lot of everyday speech. Learn rare words first and you may know them well but still not follow a simple sentence.
The 1000 Words course orders its words from the very common to the useful. Words come with their translation and audio, so you recognise them when you hear them, not only when you see them written.
Knowing a word today is not enough. Repeat the most common words in short sessions over several days. With spaced repetition and quizzes, they move from short-term memory into words you recall automatically.
Most common words are available for 33 languages. Start with the language you want to speak first, and add another one once the first feels comfortable.